Groovy unit tests always recompiled by GMavenPlus plugin

[Jan Peremsky]

Hi, 

in my maven based project with mixed test sources (java + groovy) at each build all the groovy based tests are recompiled again and again.

While as java sources recompilation is skipped - if there are no changes - groovy sources are always considered eligible for recompilation and recompiled each time mvn build is executed :-(

Is it a feature or bug?

Is there a way of how to configure maven-compiler-plugin together with gmavenplus-plugin to detect there are no changes?

I'm using java 12 to compile java sources. (but used to use java 8 and 11 with the same behaviour)

I'm using groovy 2.5.7 to compile my sources.

An excerpt from my pom can be seen below.

Thanks Jan

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.1</version>
    <configuration>
        <useIncrementalCompilation>true</useIncrementalCompilation>
        <parameters>true</parameters>
        <compilerArgs>
            <arg>-Xpkginfo:always</arg>
        </compilerArgs>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>org.ow2.asm</groupId>
            <artifactId>asm</artifactId>
            <version>7.1</version>
        </dependency>
    </dependencies>
</plugin>
<plugin>
    <groupId>org.codehaus.gmavenplus</groupId>
    <artifactId>gmavenplus-plugin</artifactId>
    <version>1.7.1</version>
    <executions>
        <execution>
            <goals>
                <goal>addTestSources</goal>
                <goal>compileTests</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <invokeDynamic>true</invokeDynamic>
        <testSources>
            <testSource>
                <directory>${project.basedir}/src/test/java</directory>
                <includes>
                    <include>**/*.groovy</include>
                </includes>
            </testSource>
        </testSources>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>org.codehaus.groovy</groupId>
            <artifactId>groovy-all</artifactId>
            <version>${groovy.version}</version>
            <type>pom</type>
        </dependency>

    </dependencies>
</plugin>

[Keegan Witt]

It's been a while since I've looked at what work has done on incremental compilation.  I'll need to do some more research before I can provide a complete answer.  I know there used to be a number of issues preventing this from working correctly, which is part of why I hadn't pursued it in the past.  But I'm uncertain whether these issues are still obstacles or not...

-Keegan